Automatic quantification of left ventricular function by medical students using ultrasound.

BACKGROUND: Automatic analyses of echocardiograms may support inexperienced users in quantifying left ventricular (LV) function. We have developed an algorithm for fully automatic measurements of mitral annular plane systolic excursion (MAPSE) and mitral annular systolic (S') and early diastolic (e') peak velocities. We aimed to study the influence of user experience of automatic measurements of these indices in echocardiographic recordings acquired by medical students and clinicians. METHODS: We included 75 consecutive patients referred for echocardiography at a university hospital. The patients underwent echocardiography by clinicians (cardiologists, cardiology residents and sonographers), who obtained manual reference measurements of MAPSE by M-mode and of S' and e' by colour tissue Doppler imaging (cTDI). Immediately after, each patient was examined by 1 of 39 medical students who were instructed in image acquisition on the day of participation. Each student acquired cTDI recordings from 1 to 4 patients. All cTDI recordings by students and clinicians were analysed for MAPSE, S' and e' using a fully automatic algorithm. The automatic measurements were compared to the manual reference measurements. RESULTS: Correct tracking of the mitral annulus was feasible in 50 (67%) and 63 (84%) of the students' and clinicians' recordings, respectively (p = 0.007). Image quality was highest in the clinicians' recordings. Mean difference ± standard deviation of the automatic measurements of the students' recordings compared to the manual reference was - 0.0 ± 2.0 mm for MAPSE, 0.3 ± 1.1 cm/s for S' and 0.6 ± 1.4 cm/s for e'. The corresponding intraclass correlation coefficients for MAPSE, S' and e' were 0.85 (good), 0.89 (good) and 0.92 (excellent), respectively. Automatic measurements from the students' and clinicians' recordings were in similar agreement with the reference when mitral annular tracking was correct. CONCLUSIONS: In case of correct tracking of the mitral annulus, the agreement with reference for the automatic measurements was overall good. Low image quality reduced feasibility. Adequate image acquisition is essential for automatic analyses of LV function indices, and thus, appropriate education of the operators is mandatory. Automatic measurements may help inexperienced users of ultrasound, but do not remove the need for dedicated education and training.

Normal ranges for automatic measurements of tissue Doppler indices of mitral annular motion by echocardiography. Data from the HUNT3 Study.

BACKGROUND: Automatic quantification of left ventricular (LV) function could enhance workflow for cardiologists and assist inexperienced clinicians who perform focused cardiac ultrasound. We have developed an algorithm for automatic measurements of the mitral annular plane systolic excursion (MAPSE) and peak velocities in systole (S') and early (e') and late (a') diastole. We aimed to establish normal reference values for the automatic measurements and to compare them with manual measurements. METHODS AND RESULTS: Healthy participants (n = 1157, 52.5% women) from the HUNT3 cross-sectional population study in Norway were included. The mean age ± standard deviation (SD) was 49 ± 14 (range: 19-89) years. The algorithm measured MAPSE, S', e', and a' from apical 4-chamber color tissue Doppler imaging (cTDI) recordings. The manual measurements were obtained by two echocardiographers, who measured MAPSE by M-mode and the velocities by cTDI. For men and women, age-specific reference values were created for groups (mean ± 1.96SD) and by linear regression (mean, 95% prediction interval). Age was negatively correlated with MAPSE, S', and e' and positively correlated with a'. There were small differences between genders. Normal reference ranges were created. The coefficients of variation between automatic and manual measurements ranged from 5.5% (S') to 11.7% (MAPSE). CONCLUSION: Normal reference values for automatic measurements of LV function indices are provided. The automatic measurements were in line with the manual measurements. Implementing automatic measurements and comparison with normal ranges in ultrasound scanners can allow for quick and precise interpretation of LV function.

Blood flow imaging in transesophageal echocardiography during atrial septal defect closure: a comparison with the current references.

BACKGROUND: Flow visualization before transcatheter atrial septal defect (ASD) closure is essential to identify the number and size of ASDs and to map the pulmonary veins (PV). Previous reports have shown improved visualization of ASD and PV using blood flow imaging (BFI), which supplements color Doppler imaging (CDI) with angle-independent information of flow direction. In this study, we compared transesophageal BFI with the current references in ASD sizing (balloon stretched diameter, BSD) and PV imaging (pulmonary angiography). METHODS: In this prospective study, 28 children were examined with transesophageal echocardiography (TEE) including BFI of the secundum ASD and the PV before interventional ASD closure. The maximum ASD diameter measured with BFI by 4 observers was compared to the corresponding BSD and CDI measurements. The repeatability of the BFI measurements was calculated as the residual standard deviation. BFI of the PV was compared to PV angiography. RESULTS: The mean maximum diameter measured by BFI was 12.1 mm (±SD 2.4 mm). The corresponding BSD and CDI measurements were 15.9 mm (±SD 3.0 mm) and 11.8 mm (±SD 2.5 mm), respectively. The residual standard deviation was 1.2 mm. Compared to PV angiography, the sensitivity of BFI in detecting the correct entry of the PV was 0.96 (95% CI: 0.82-1.0). CONCLUSION: Transesohageal echocardiography with BFI of the PV agreed well with pulmonary angiography. BFI had lower estimates for ASD size than BSD, but with acceptable 95% limits of agreement. The repeatability of the BFI measurements was close to the inherent ultrasound measurement error.

Feasibility and accuracy of point-of-care pocket-size ultrasonography performed by medical students.

BACKGROUND: Point-of-care ultrasound performed by clinicians is a useful supplement in the treatment and assessment of patients. We aimed to investigate whether medical students with minimal training were able to successfully acquire and interpret ultrasound images using a pocket-size imaging device (PSID) as a supplement to their clinical practice. METHODS: Thirty 5th year (of six) medical students volunteered to participate. They were each given a personal PSID device to use as a supplement to their physical examination during their allocated hospital terms. Prior to clinical placement the students were given three evenings of hands-on training with PSID by a board certified radiologist/cardiologist, including three short lectures (<20 min). The students were shown basic ultrasound techniques and taught to assess for basic, clinically relevant pathology. They were specifically instructed to assess for the presence or absence of reduced left ventricular function (assessed as mitral annular excursion < 10 mm), pericardial effusion, pleural effusion, lung comets, hydronephrosis, bladder distension, gallstones, abdominal free-fluid, cholecystitis, and estimate the diameter of abdominal aorta and inferior vena cava. RESULTS: A total of 211 patients were examined creating 1151 ultrasound recordings. Acceptable organ presentation was 73.8% (95% CI 63.1-82.6) for cardiovascular and 88.4% (95% CI: 80.6-93.6) for radiological structures. Diagnostic accuracy was 93.5% (95% CI: 89.0-96.2) and 93.2% (95% CI: 87.4-96.5) respectively. CONCLUSION: Medical students with minimal training were able to use PSID as a supplement to standard physical examination and successfully acquire acceptable relevant organ recordings for presentation and correctly interpret these with great accuracy.

Effects of hypothermia on the disposition of morphine, midazolam, fentanyl, and propofol in intensive care unit patients.

Therapeutic hypothermia (TH) may induce pharmacokinetic changes that may affect the level of sedation. We have compared the disposition of morphine, midazolam, fentanyl, and propofol in TH with normothermia in man. Fourteen patients treated with TH following cardiac arrest (33-34°C) were compared with eight matched critically ill patients (36-38°C). Continuous infusions of morphine and midazolam were stopped and replaced with infusions of fentanyl and propofol to describe elimination and start of infusion pharmacokinetics, respectively. Serial serum and urine samples were collected for 6-8 hours for validated quantification and subsequent pharmacokinetic analysis. During TH, morphine elimination half-life (t(1/2)) was significantly higher, while total clearance (CL(tot)) was significantly lower (median [semi-interquartile range (s-iqr)]): t(1/2), 266 (43) versus 168 (11) minutes, P < 0.01; CL(tot), 1201 (283) versus 1687 (200) ml/min, P < 0.01. No significant differences were seen for midazolam. CL(tot) of fentanyl and propofol was significantly lower in hypothermic patients [median (s-iqr)]: fentanyl, 726 (230) versus 1331 (678) ml/min, P < 0.05; propofol, 2046 (305) versus 2665 (223) ml/min, P < 0.05. Compared with the matched, normothermic intensive care unit patients, t(1/2) of morphine was significantly higher during TH. CL(tot) was lower during TH for morphine, fentanyl, and propofol but not for midazolam. Reducing the infusion rates of morphine, fentanyl, and propofol during TH is encouraged.

Assessment of left ventricular function by GPs using pocket-sized ultrasound.

BACKGROUND: Assessment of left ventricular (LV) function with echocardiography is mandatory in patients with suspected heart failure (HF). OBJECTIVES: To investigate if GPs were able to evaluate the LV function in patients at risk of developing or with established HF by using pocket-sized ultrasound (pUS). METHODS: Feasibility study in general practice, seven GPs in three different Norwegian primary care centres participated. Ninety-two patients with reduced or at risk of developing reduced LV function were examined by their own GP using pUS. The scan (<5 minute) was done as part of a routine appointment. A cardiologist examined the patients <30 minutes afterwards with both a laptop scanner and pUS. Measurements of the septal mitral annular excursion (sMAE) were compared. RESULTS: In 87% of the patients, the GPs were able to obtain a standard view and measure the sMAE. There was a non-significant mean difference in sMAE between GP pUS and cardiologist laptop scanner of -0.15 mm 95% confidence interval (-0.60 to 0.30) mm. A comparison of the pUS recordings and measurements of sMAE made by GP versus cardiologist revealed a non-significant mean difference with acceptable 95% limits of agreement (-0.26 ± 3.02 mm). CONCLUSIONS: With tailored training, GPs were able to assess LV function with sMAE and pUS. pUS, as a supplement to the physical examination, may become an important tool in general practice.

Diagnostic influence of cardiovascular screening by pocket-size ultrasound in a cardiac unit.

AIMS: We aimed to study the diagnostic influence of adding a routine cardiovascular ultrasound screening of the cardiac anatomy and function, the pericardium, the pleura and the abdominal great vessels by the new pocket-size ultrasound device (pUS) with grey scale and colour Doppler imaging. METHODS AND RESULTS: In 119 randomly selected patients admitted to a cardiac unit at a non-university hospital, routinely adding a cardiovascular ultrasonography of only 4.4 min with a pocket-size device corrected the primary diagnosis in 16% of patients. In addition, 29% had the primary diagnosis verified and in 10% an additional important diagnosis was made. Higher age predicted any diagnostic influence of pUS screening with an increase of 61% (P=0.003) per 10 years of higher age. Overall, the pUS screening had a sensitivity and specificity with respect to detecting at least moderate pathology of 97 and 93%. Positive and negative predictive values were 93 and 87%, respectively. In the sub-group of subjects with a change in the primary diagnosis following pUS there was no false-negative or false-positive findings. CONCLUSION: Screening by pUS assessed vascular and cardiac anatomy and function accurately and enabled correction of the diagnosis in 16% of patients admitted to a cardiac unit. In 55% of the participants, the cardiovascular ultrasound screening had important diagnostic influence. We suggest that it would be appropriate to implement strategies and systems for routinely adding an ultrasound cardiovascular examination to patients in cardiac units.

Feasibility and reliability of point-of-care pocket-sized echocardiography.

AIMS: To study the reliability and feasibility of point-of-care pocket-sized echocardiography (POCKET) at the bedside in patients admitted to a medical department at a non-university hospital. METHODS AND RESULTS: One hundred and eight patients were randomized to bedside POCKET examination shortly after admission and later high-end echocardiography (HIGH) in the echo-lab. The POCKET examinations were done by cardiologists on their ward rounds. Assessments of global and regional left ventricular (LV) function, right ventricular (RV) function, valvular function, left atrial (LA) size, the pericardium and pleura were done with respect to effusion and measurements of inferior vena cava (IVC) and abdominal aorta (AA) were performed. Correlations between POCKET and HIGH/appropriate radiological technique for LV function, AA size and presence of pericardial effusion were almost perfect, with r ≥ 0.92. Strong correlation (r ≥ 0.81) was shown for RV and valvular function, except for grading of aortic stenosis (r = 0.62). The correlations were substantial for IVC and LA dimensions. Median time used for bedside screening with POCKET was 4.2 min (range: 2.3-13.0). There was excellent feasibility for cardiac structures and pleura, which was assessed to satisfaction in ≥ 94% of patients. Lower feasibility (71-79%) was seen for the abdominal great vessels. CONCLUSION: Point-of-care semi-quantitative evaluation of cardiac anatomy and function showed high feasibility and correlation with the reference method for most indices. Pocket-sized echocardiographic examinations of ∼4 min length, performed at the bedside by experts, offers reliable assessment of cardiac structures, the pleural space and the large abdominal vessels. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov; unique ID: NCT01081210.

A 50-year-old man with eosinophilia and cardiomyopathy: need for endomyocardial biopsy?

A 50-year-old man was admitted with a suspected acute coronary syndrome. The coronary angiogram, however, was normal. He was found to have a cardiomyopathy and eosinophilia. The diagnosis was established as a perimyocarditis secondary to the Churg-Strauss syndrome. An important question is whether an endomyocardial biopsy should have been performed.

High prevalence of subclinical rheumatic heart disease in pregnant women in a developing country: an echocardiographic study.

OBJECTIVES: Pregnant women with rheumatic heart disease (RHD) carry a high risk of morbidity and mortality. In this study the prevalence of subclinical RHD in pregnant women in Keren, Eritrea was assessed using echocardiography. METHODS AND RESULTS: A prospective cross sectional survey of pregnant women attending a midwife consultation was carried out by two specially trained medical students and an experienced cardiologist. The women were screened by the medical students using echocardiography. All recordings were reviewed and evaluated by the experienced cardiologist before a final diagnosis was given. Eight of the 348 screened women had definite RHD. This corresponds to a prevalence of 2.3%, 95% CI (0.7-3.9). CONCLUSION: 2.3% of the pregnant women in Keren were found to have subclinical RHD.

Does a new ultrasound flow modality improve visualization of neonatal pulmonary veins?

BACKGROUND: Blood flow imaging is a new ultrasound modality that supplements color Doppler imaging with angle-independent information of flow direction that is not influenced by velocity aliasing. This is done by visualizing the blood speckle movement superimposed on the color Doppler images. This study aimed to investigate whether this method improves the visualization of the pulmonary veins in neonates. METHODS: Twenty-six neonates with suspected congenital heart disease were prospectively examined with echocardiography and blood flow imaging of the pulmonary veins after parental consent. For each patient, blood flow imaging and color Doppler imaging cine loops were presented to four observers (pediatric cardiologist/cardiologists) in a random order. Questions regarding the pulmonary venous connections and the overall quality of the pulmonary vein imaging were evaluated on a visual analogue scale from 0 (worst) to 100 (best). The methods were compared within each observer using the Wilcoxon's exact signed-rank test. RESULTS: Blood flow imaging (color Doppler imaging combined with the blood speckle movement) was consistently ranked as better than conventional color Doppler imaging for visualization of the pulmonary veins for all observers (all P-values < 0.002). CONCLUSION: Blood flow imaging may improve the visualization of the pulmonary veins in neonates.

Left ventricular myocardial function during the acute phase of a subarachnoid haemorrhage.

OBJECTIVES: Previous reports suggest that left myocardial ventricular function changes during the course of a subarachnoid haemorrhage. The aim of this study was to evaluate left myocardial ventricular function with tissue Doppler echocardiography at two time points during the acute phase of a subarachnoid haemorrhage. DESIGN: Eighteen consecutive patients (median 52 years, range 33-74) with spontaneous subarachnoid haemorrhage and no history of heart disease were examined at 1-5 days and at 6-11 days following ictus. Eighteen control subjects were included for comparison (52 years, 32-72). RESULTS: Tissue Doppler indices of left ventricular contractility were higher in patients than in controls at both examinations (p<0.001). Indices of left ventricular stroke volume were elevated compared to controls at examination 1 (p<0.05), but not at examination 2. Early diastolic relaxation rate decreased from examination 1 to 2 (p=0.001). Three patients had increased troponin T (range 0.010-0.131 microg/l). CONCLUSION: In patients with subarachnoid haemorrhage, systolic and diastolic function is increased compared to healthy controls, suggesting a hyperdynamic and hypervolemic circulation.

Real-Time Standard View Classification in Transthoracic Echocardiography Using Convolutional Neural Networks.

Transthoracic echocardiography examinations are usually performed according to a protocol comprising different probe postures providing standard views of the heart. These are used as a basis when assessing cardiac function, and it is essential that the morphophysiological representations are correct. Clinical analysis is often initialized with the current view, and automatic classification can thus be useful in improving today's workflow. In this article, convolutional neural networks (CNNs) are used to create classification models predicting up to seven different cardiac views. Data sets of 2-D ultrasound acquired from studies totaling more than 500 patients and 7000 videos were included. State-of-the-art accuracies of 98.3% ± 0.6% and 98.9% ± 0.6% on single frames and sequences, respectively, and real-time performance with 4.4 ± 0.3 ms per frame were achieved. Further, it was found that CNNs have the potential for use in automatic multiplanar reformatting and orientation guidance. Using 3-D data to train models applicable for 2-D classification, we achieved a median deviation of 4° ± 3° from the optimal orientations.

Automatic Measurements of Mitral Annular Plane Systolic Excursion and Velocities to Detect Left Ventricular Dysfunction.

The purpose of the study described here was to evaluate an automatic algorithm for detection of left ventricular dysfunction, based on measurements of mitral annular motion indices from color tissue Doppler apical four-chamber recordings. Two hundred twenty-one patients, among whom 49 had systolic and 11 had diastolic dysfunction, were included. Echocardiographic evaluation by cardiologists was the reference. Twenty patients were also examined by medical students. The ability of the indices to detect systolic and diastolic dysfunction were compared in receiver operating characteristic analyses, and the agreement between automatic and reference measurements was evaluated. Mitral annular plane systolic excursion ≤10 mm detected left ventricular dysfunction with 82% specificity, 76% specificity, 56% positive predictive value and 92% negative predictive value. The automatic measurements acquired from expert recordings better agreed better with the reference than those acquired from student recordings. We conclude that automatic measurements of systolic mitral annular motion indices can be helpful in detection of left ventricular dysfunction.

Realtime Automatic Assessment of Cardiac Function in Echocardiography.

Assessment of cardiac function by echocardiography is challenging for nonexperts. In a patient with dyspnea, quantification of the mitral annular excursion (MAE) and velocities is important for the diagnosis of heart failure. The displacement of the atrioventricular (AV) plane is a good indicator of systolic left ventricular function, while the peak velocities give supplementary information about the systolic and diastolic function. By measuring these parameters automatically, a preliminary diagnosis can be given by the nonexpert. We propose an automatic algorithm to localize the mitral annular points in an apical four-chamber view and estimate the MAE, as well as the systolic, early diastolic, and late diastolic tissue peak velocities, by using a deformable ventricle model for orientation and tissue Doppler data for tracking. Automatic parameter estimates from 367 tissue Doppler recordings were compared to reference measurements by experienced cardiologists to assess the accuracy of the estimation, as well as the ability to correctly detect reduced MAE, which we defined as less than 10 mm. The dataset consisted of 200 recordings from a patient population and 167 healthy from a population study. When considering the average of the septal and lateral values, the estimation error for the MAE had a standard deviation of 2.1 mm, which was reduced to 1.9 mm when excluding recordings for which the automatic segmentation failed to locate the AV plane (41 recordings). The corresponding standard deviations for the peak velocities were around 1 cm/s. The classification of MAE was correct in 90% of the cases and had a sensitivity of 83% and a specificity of 92%. We conclude that the algorithm has good accuracy and note that the estimation error for the MAE was comparable to interobserver and methodology agreements reported in the literature.

ECG patterns in early pulseless electrical activity-Associations with aetiology and survival of in-hospital cardiac arrest.

INTRODUCTION: Pulseless electrical activity (PEA) is an increasingly common presentation in cardiac arrest. The aim of this study was to investigate possible associations between early ECG patterns in PEA and the underlying causes and survival of in-hospital cardiac arrest (IHCA). METHODS: Prospectively observed episodes of IHCA presenting as PEA between January 2009 and august 2013, with a reliable cause of arrest and corresponding defibrillator ECG recordings, were analysed. QRS width, QT interval, Bazett's corrected QT interval, presence of P waves and heart rate (HR) was determined. QRS width and HR were considered to be normal below 120ms and within 60-100 cardiac cycles per minute, respectively. RESULTS: Fifty-one episodes fulfilled the inclusion criteria. The defibrillator was attached after a median of one minute (75th percentile; 3min) after the onset of arrest. Ninety percent (46/51) had widened QRS complexes, 63% (32/51) were defined as 'wide-slow' due to QRS-widened bradycardia, and only 6% (3/51) episodes were categorized as normal. No unique cause-specific ECG pattern could be identified. Further 7 episodes with a corresponding defibrillator file, but without a reliable cause, were included in analysis of survival. Abnormal ECG patterns were seen in all survivors. None of the patients with 'normal' PEA survived. CONCLUSION: Abnormal ECG patterns were frequent at the early stage of in-hospital PEA. No unique patterns were associated with the underlying causes or survival.

Recognizing the causes of in-hospital cardiac arrest--A survival benefit.

BACKGROUND: The in-hospital emergency team (ET) may or may not recognize the causes of in-hospital cardiac arrest (IHCA) during the provision of cardiopulmonary resuscitation (CPR). In a previous 4.5-year prospective study, this rate of recognition was found to be 66%. The aim of this study was to investigate whether survival improved if the cause of arrest was recognized by the ET. METHODS: The difference in survival if the causes were recognized versus not recognized was estimated after propensity score matching patients from these two groups. RESULTS: Overall survival to hospital discharge was 25%. After propensity score matching, the benefit of recognizing the cause regarding 1-hour survival of the episode was 29% (p<0.01), and 19% regarding hospital discharge, respectively. Variables commonly known to affect the outcome after cardiac arrest were found to be balanced between the two groups. The largest difference was found in patients with non-cardiac causes and non-shockable presenting rhythms. Patient records and pre-arrest clinical symptoms were the information sources most frequently utilized by the ET to establish the causes of arrest. CONCLUSIONS: Patients suffering an IHCA showed a substantial survival benefit if the causes of arrest were recognized by the ET. Patient records and pre-arrest clinical symptoms were the sources of information most frequently utilized in these instances.

Causes of in-hospital cardiac arrest - incidences and rate of recognition.

BACKGROUND AND METHODS: Do emergency teams (ETs) consider the underlying causes of in-hospital cardiac arrest (IHCA) during advanced life support (ALS)? In a 4.5-year prospective observational study, an aetiology study group examined 302 episodes of IHCA. The purpose was to investigate the causes and cause-related survival and to evaluate whether these causes were recognised by the ETs. RESULTS: In 258 (85%) episodes, the cause of IHCA was reliably determined. The cause was correctly recognised by the ET in 198 of 302 episodes (66%). In the majority of episodes, cardiac causes (156, 60%) or hypoxic causes (51, 20%) were present. The cause-related survival was 30% for cardiac aetiology and 37% for hypoxic aetiology. The initial cardiac rhythm was pulseless electrical activity (PEA) in 144 episodes (48%) followed by asystole in 70 episodes (23%) and combined ventricular fibrillation/ventricular tachycardia (VF/VT) in 83 episodes (27%). Seventy-one patients (25%) survived to hospital discharge. The median delay to cardiopulmonary resuscitation (CPR) was 1min (inter-quartile range 0-1min). CONCLUSIONS: Various cardiac and hypoxic aetiologies dominated. In two-thirds of IHCA episodes, the underlying cause was correctly identified by the ET, i.e. according to the findings of the aetiology study group.